A silicon bar 10 cm long with a crosssection of 2 mm x 10 mm

A silicon bar 10 cm long with a cross-section of 2 mm x 10 mm and doped p-type with N_a = 10^17/cm^ 3is cooled at one end to 0 Degree C and heated at the other end to 100 Degree C. Is the silicon bar in equilibrium? Suppose an ideal voltmeter is connected across the terminals. What voltage will it measure? Recall that an ideal voltmeter has infinite resistance. Suppose an ideal ammeter is connected across the terminals. What current will it measure? Recall that an ideal ammeter has zero resistance.

Solution

a) the silicon bar is not in equilibrium, because of temperature difference between the two ends.

b) the voltmeter will measure the voltage cause by the thermal movement of electrons i,e minorities in this case.

c) the current measured by the ammeter will be due to the motion of electrons in conduction band, which have gained the thermal energy in moving from valence to conduction band.